Paradise (1986)

Viktor and Angelika are a straight couple. He is a professor of veterinary science and she has studied art history. Both are more interested in their hobbies and professions than in each other; also, Viktor isn't terribly interested in satisfying his wife anymore. Their upright relationship changes dramatically when Viktor gets to know Lotte, a former school friend of Angelika's. Back in school, Lotte would have done anything for Angelika.